P. Clay Sherrod Oct 11 7:13 PM
----- Original Message -----
From: "Bill Gray pluto@... [guide-user]"
<guide-user@yahoogroups.com>
To: <guide-user@yahoogroups.com>
Sent: Tuesday, October 11, 2016 7:58 PM
Subject: Re: [guide-user] Searching URAT1 Catalogue (and Gaia-DR1)
> Hi Ted,
>
> You can use Go To... Object Name (or just hit Ctrl-B) and Guide will
> bring up an "Enter object name:" dialog. In this, you can enter something
> resembling
>
> 2U314-15926
> 3UC314-15926
> 4U314-15926
>
> For UCAC2, the "standard" prefix was 2U; for UCAC3, it was 3UC (I think
> somebody was already using 3U for something else); then, with UCAC4, we
> went back to 4U.
>
> That prefix is followed by a "zone number". All UCACs were split into
> zones in declination; for UCAC2 and UCAC3, the zones were 0.5 degrees high.
> That made for zone numbers from 1 to 360 for UCAC3. UCAC2 only got up to
> about declination +46 or something like that, so the zone numbers stopped
> somewhere around 288.
>
> UCAC4 was split into 0.2 degree strips in declination, so the zone
> numbers run from 1 to 900.
>
> After the zone number, there's a '-', then the number within that zone.
>
> Just a heads up : as many of you doubtless know, the first data release
> for Gaia (Gaia-DR1) has recently been posted. This provides very precise
> astrometry and photometry for about a billion stars.
>
> This will eventually make all other star catalogs obsolete (well, except
> for some very bright stars that were saturated in Gaia). There are some
> limits at present : Gaia hasn't been observing for very long, so it
> essentially
> has only measured "where the stars are now". Parallaxes and proper motions
> will come in a subsequent release. Gaia-DR1 only gives data for the cleaner
> cases; they haven't tried to sort out the tangled situations with double
> and multiple stars. Still, it's what we all should be using for (for
> example) astrometric reductions, where the fact that only the "best"
> positions are given is a benefit, not a drawback.
>
> There are two other small hitches to Gaia. First, the raw data files,
> provided here :
>
> http://cdn.gea.esac.esa.int/Gaia/gaia_source/csv/
>
> tip the scales at over 200 GBytes, in compressed form (still larger
> once decompressed, about 500 GBytes). The data are split into 5231 files,
> each containing 170579 stars (except for the last one, which just contains
> the last few leftover stars).
>
> The second hitch is that the order of the stars looks to be almost
> completely random. It isn't; the stars are ordered according to the
> HEALPix 'nested' scheme. This is a theoretically elegant scheme that
> could speed up access to the data. That's the theory; in practice,
> dealing with this is beyond horrible. I expect that all practical use of
> the raw data will involve downloading the files and sorting them into
> declination zones, similar to all UCACs and Ax.0 and B1.0. (Why ESA
> didn't do that in the first place baffles me. I think someone fell in
> love with the mathematical elegance of the HEALPix scheme.) Fortunately,
> getting the data sorted into declination zones isn't all that difficult.
>
> However, I expect most of us will _not_ be downloading 200 GBytes and
> then keeping it on a half terabyte of hard drive. Instead, we'll just
> download Gaia-DR1 data on an "as needed" basis for a given area, from
> VizieR. I'll be setting up Guide to do that.
>
> -- Bill
>
> On 2016-10-11 16:17, Ted Blank tedblank@... [guide-user] wrote:
>>
>>
>> Hi Bill, when you get a moment could you remind us what formats Guide expects
>> for the UCAC one through four star designations?
>>
>> I cannot seem to find any specific examples in the Help files.
>>
>> Best regards,
>> Ted Blank
>>
>> (603) 817 9814 (cell)
>>
>> Sent from my iPhone
>>
>> On Oct 11, 2016, at 3:00 PM, Bill Gray pluto@...
>> <mailto:pluto@...> [guide-user] <guide-user@yahoogroups.com
>> <mailto:guide-user@yahoogroups.com>> wrote:
>>
>>>
>>>
>>> Hi all,
>>>
>>> The method Denis mentions will work, _if_ the URAT star is among
>>> those displayed on-screen. For URAT1, Guide will extract only that
>>> area from the binary catalog, expanding it into the ASCII file
>>> 'urat.txt'. It is that file which Guide displays, using the TDF
>>> (text definition file) system. And it's that file at which Guide
>>> will look when you use Go To... Go to .TDF Object command.
>>>
>>> I put in some extra code so that Go To... Object Name could recognize
>>> UCAC-1 through 4 designations, and A1.0 and A2.0 and B1.0 designations,
>>> whether the object was on-screen or not. I'll take another look at
>>> getting URAT1 similarly recognized.
>>>
>>> -- Bill
>>>
>>> On 10/09/2016 03:03 PM, Denis boucherd@...
>>> <mailto:boucherd@...> [guide-user] wrote:
>>> >
>>> >
>>> > Try under GO TO, Go To .TDF Object, select URAT1 in user database and
>>> > press OK then enter the star number in search window.
>>> >
>>> > That should work.
>>> >
>>> > On 09-Oct-16 11:40 AM, stjohnrobinson@...
>>> > <mailto:stjohnrobinson@...> [guide-user] wrote:
>>> >> Hello Denis,
>>> >>
>>> >> I think you have misunderstood or I did not make myself clear enough.
>>> >>
>>> >> I have the URAT1 data set, and have configured Guide to display the
>>> >> URAT1 stars successfully, what I am now trying to achieve is to
>>> >> correctly format a search term that can be entered into the GOTO
>>> >> command: -
>>> >>
>>> >> i.e 1URAT547-642315 this is a URAT1 star that guide will display,
>>> >> amongst many others, however if you then enter the same format into
>>> >> the GOTO command, it returns 'Not a valid object'.
>>> >>
>>> >> I have tried variations on a theme as it where but with out success.
>>> >> So thanks for the response, I will have to see if Bill can enlighten me!!
>>> >>
>>> >> best regards
>>> >> stjohn
>>> >>
>>> >
>>> >
>>> >
>>> >
>>>
>>
>>
>>
>
>
> ------------------------------------
> Posted by: Bill Gray <pluto@...>
> ------------------------------------
>
> To unsubscribe from this group, send an empty email to:
> guide-user-unsubscribe@egroups.com
> ------------------------------------
>
> Yahoo Groups Links
>
>
>